Specs:
This is cheap insurance for your frame. A dropped chain can cause havoc on your chainstay and race-day. At only 5.6grams including all hardware this is lighter than the bolt and washer it replaces (Dura-Ace ). Ok so your front deraillleur should be setup perfectly right? So there is no need for the chain to drop? Add in a rough CX course, potholes, chip and seal and council neglected roads, Its only a matter of time you feel the fun of a dropped chain and usually a subtraction of paint with it.
The chain deflector mounts on the outside of the frame's braze-on tab and in-between the supplied bolt and concave washer. It is gracefully angled so it will catch the chain from the highest point and slide it back to the inner ring. Set the Deflector up close to the inner ring and then there is no chance of the chain heading off the track. The bolt is a T25. The Silver coloured deflector is supplied with a red anodized bolt while all the others use colour coded bolts.
No more chewed out chain stays.